Fluid actuated press



June 22, 1965 R c, HowARD ETAL 3,190,215

FLUID ACTUAT'ED PRESS Filed may 11, 1964 2 shets-sheet 1 i INVENTORS g @E6/NMD c. Hon/A20 /Z LAWRENCE #Mapa11/51.1., JP.

BYW-fm June 22, 1965 R. c. HOWARD ETAL 3,190,215

` FLUID AGTUATED PRESS Filed May 1l, 1964 2 Sheets-Sheet 2' wmammmw 70 7* 74 Q FIG. 5

5 zu i v i 35? 7 v 7 51kg/ i United States Patent Office 3,193,215 Patented Jurre 22, 1965 3,1%,215 FMH?) ACTUATED PRESS Reginald C. Howard, 11924 Montana Ave., Apt. 5, Los Angeles, Calif., and Lawrence W. McDowell, r., 4223 Patrice Road, Newport Beach, Calif.

File-d May 11, 1%4, Ser. No. 366,439 1t? `Claims. (l. lull- 257) The present invention relates to a uid actuated press, andmore particularly to a press which is actuated by an eXpansi-ble, unarticulated container or bag.

A conventional press includes a stationary bed, a plurality of vertical guide posts iixed at their lower extremities to the bed, and a ram whichis vertically slidably mounted on the posts and defines a die set or Working area with the bed. in many applications it is important that the mechanism or agency which aotuates the ram'toward the bed to performthe working operation be immediately and sensitively responsive to the control system. Sensitivity of response is very important where a repetitive operation is involved, such as in the case of work operations that require several hundred ram strokes per minute, and Where the forming operation must be accomplished in accordance with a precise and predetermined time-pressure cycle. Most hydraulicdly operated presses of the prior art characteristically possess an undesirable lag in ram response subsequent to initiation of hydraulic fluid flow into the actuating mechanism. Vllresses utilizing iniiatable bellows to effect ram movement also are characterized by a lag in ram operation, primarily because in the collapsed state of the bellows there is an internal space which must lirst be illed with pressurized fluid during each cycle before the bellows can be internally pressurized to the level sufficient to drive the ram.

Accordingly,it is an object ofthe present invention to provide a fluid actuated press which is sensitively re-V sponsive to the agency or medium ot' actuation whereby a lag between movement of the ram subsequent to operation of the actuating medium is substantially eliminated and precise time-pressure cycles of operation are afforded.

Another object of the invention is to provide an improved actuator for use with a press having a die set assembly which includes a stationary bed, a plurality of vertical guide posts xed at their lower extremities to the bed, and a ram vertically slidably'rnounted on the posts and defining a die set area with the bed, theractuator being adapted for mounting adjacent the upper extremities of the guide posts for actuation of the ram 'toward the press bed, and further adapted to be quickly and easily removed from the die set assembly for use with an identical die set assembly. in this manner, one actuator may be used with a plurality of different die set assemblies. Ordinarily, a certain amount of fset-up time and adjustment is required to precisely locate a set of dies between the ram and press bed. However, with the arrangement just described a number of die set assemblies, Veach including a different die set, can be stored for production of a variety of parts at a moments notice. -All that need be clone is to mount the actuator to the particular die set assembly de-Y sired. In most cases, the cost of the ram, press -bed and vertical posts stored with each die set is', considerably less than the labor cost whichwould be required to set up the dies each time in a conventional press.

Another object of the invention is to utilize an actuator which includes a flexible, unarticulated ,bag for actuation responding movement of the ram. Accordingly, the ram is sensitively responsive to any introduction of pressurized uid into the bag whereby, for example, a precise timepressure cycle may be followed and close control is aiorded over Ia work operation requiring rapid, relatively short strokes of the ram, and all without expensive control equipment.

Another object of the invention is the provision of an actuator for a press of the above-described character which is relatively simple to operate, inexpensive to manufacture, and characterized by an extended service life.

Other objects and features of the invention will become apparent from consideration of the following description taken in connection with the accompanying drawings, in which: f

FIG. l is a perspective view of a fluid actuated press incorporating anractuator according to the present invention;

FIG. 2 is a view taken along the line 2 2 of FIG. l;

EEG. 3 is an enlarged detail View of the encircled area designated bythe numeral 3 in FIG. 2;

FIG. 4 is an enlarged detail View taken along the line 4 4 of FIG. 2;

FIG. 5 is an enlarged detail view taken along the line 5-.-5 of FIG. l; v

Fl. 6 is a view taken along the line 6-6 of FIG. 5; and

7 is a View taken along the line 7-7 of FIG. 5.

Referring now to the drawings, there is illustrated a.V

press having a die set assembly 1G which includes a stationary press bed 12; a plurality of vertical guide posts 14 fixed at their lower extremities `to the bed 12; a ran 16 vertically sliclably mounted on the guide posts 14 and defining a working or die set area 18 with the press'bed 12; and an actuator Ztl operative to effect movement of the ram 1d toward and away from the press bed 12.

The actuator 2li includes, generally, a thrust plate 2,2 mounted to the guide posts 14 adjacent the upper extremities thereof; a liexible, unarticulated bag 24 to effect movement of the ram 16 toward the press bed 12 upon introduction of pressurized lluid into the bag; and fluid j pressure and control apparatus 26 for introducing uid under pressure into the bag 24. Y The die vset assembly 10 is a relatively inexpensive structure Yin which the press bed 12 is preferably rectangular in conguration, horizontally oriented, and forged or cast to provide a relatively thin supporting wall 28 dening the lower boundary of the die set area 18. The lower die of the usual die set (not shown) is attached tothe upper surface of the wall 28 by any suitable means, as will be readily apparent to those skilled in the art. The supporting wall 28 is suitably reinforced by the provision of integral reinforcing ribs 3:0` in the underside thereof, and the four corners of the rectangular supporting wall are heavier in cross-section and, eachincludes a vertically oriented bore 32 to receive the lower extremity of one of the four guide posts 14. Each such lower extremity includes an annular grooveV in which is mounted a usual snap ring 34 of a diameter larger than that of the bore 32 and received within a counter bore 35 coaxial with the bore 32. The snap rings 34 transfer to the press bed 12 the tensile forces to which the guide posts 14 are subjected during operation of the press.

The ram 16 is substantially rectangular in conguration and horizontally oriented in coplanar, coextensive relationship tothe press bed 12. Y lts lower surface defines the upper boundary of the die set area 18, and the upper die of the usual die set (not shown) is secured to this surface in thesame manner that Vthe lower die was secured to the press bed 12. Y

The ram 16 is fabricated like the press bed 12, being provided with a horizontally oriented supporting wall 38'strengthened by integral stilfeners or ribs 40. VThe four. corners of the ram 16 are of heavier cross-section and each includes a bore 42 which slidably, receives the ceiving a Ynut'46 to secure the bushing 44 to the wall 38.

This arrangement permits the guide bushings 44 to be removed when they become worn, without having to replace the whole ram 16. 1 Y

VA ilat or planar plate 48 rests upon the upper edges of the ram ribs 4t) and constitutes the lower one of the reaction surfaces against which the bag 24 acts.

The thrust plate 22 is substantially,rectangular in coniguratiomhorizontally orientedpand characterized by a Hat, planar lower` surface constituting the upper reaction surfaceV against whichV the bag 24k acts. The plate 22 includes reinforcing ribs or webs 50V radiating `from a central boss S2 to the four corners of the thrustfplat-e 22. The four corners of the thrust plate 22 are heavier in cross-section than the main portion of the plate andare each provided with a vertical bore 54 which vertically slidably receives one of the guide posts 14. This permits the thrust plate 22 tolbe vertically moved for adjustment and removal.` Any desired vertical position of the thrust plate .is maintained by pairs'of split collars 56 and 58 mounted upon diagonally opposite pairs of the guide posts 14, respectively. t Y -V As best illustrated in FIGS. through 7, each collar 56 includes a vertical slit or split-6G extending through the wall to-the interior-of thecentral bore thereof. A horizontal set screw 62 is threadably carried by the collar 56, rotation of the set screw 62 in onedirection tending to widen the split by urging apart the opposing `'faces defining the split 66. This also opens up th-e central bore and permitsV the collar to be vertically Vslidably ymoved upon the associated guide post 14.1 Conversely, rotation of the setscrew 62 in the yopposite direction releases the bias force tending to open the central bore, and the split 6i) narrows and the collar 56 tightly` grips the guide post 14, serving as a stop Vpast which the thrust plate cannot move. f v

The construction of thecollar 58 is identical tothe n construction of the collar 56 thus far described. However, each collar 56 is additionally provided with a horizontal slot or slit 64 through all but a relatively small portion 66 of the area of the collar, as best viewed in FIG. 7. A vertical bolt 68 having an enlarged Ahead portion is .received within a complemental bore and counterbore Y provided in the cornerof the thrust plate 22 adjacent the particular collar 56, and the upper extremity of the bolt 68 is threaded for dispositionwithin a threaded vertical opening provided in the collar 56 in communication with the slit 64. "Niththis arrangement, the collars 56 are adapted to grip the pair of associated, diagonally opposite guide` posts 14 and suspend theV thrust plate 22 in position and constrain it against downward slidable movement.

` The ,flexible bag 24 normally lassumes a aftypancakelike configuration between the thrust plate 22 and the ram4 16,` and is made of a material suchas rubber or the like,

Vreinforced or otherwise, and having an elastic characteristic of longitudinal,expansionrwithout significant lateral expansion' upon introduction of pressurized lluidrinto the bag. ySuch .bags are commercially available.'k The bag 24 conforms tothe bounding surfacesV Withwhich it is engaged, and is squeezed flatewithoutany appreciable .vol-A adhesively secured to a complementally tapered annular fitting '72. Y The fitting 72 includes an annular, horizonytally and radially inwardly oriented groove 74 which snugly receives a radial ange 76 forming a part of a cylindrical split.collar 78.

The collar 78 is adapted to be vertically slidably mounted upon an elongated vertical bushing `89 which is mounted within the central bore of the boss 52. l The bushing Si) includes an annular groove at its lower extremity which receives a sealing element or O-ring 82, which bears against the adjacent surface of the collar 7S and provides a fluid-tight relationship therebetween. The upper extremity of thebushing Si) is provided with an integral cap S4 which overlies the upper end of the `boss 52 and is provided with openings in alignment with threaded openings provided in the bossV 52. A pair of machine screws 861are disposedin these openings to securely mount the bushing S0 .in `position upon the boss 52.0f the thrust plate 22. Y y Y TheA upperV extremity ofv the bushing 80'is internally threadedy to receive 'the' threaded lower extremity of a conduit 88. The threaded upper extremity of the conduit ume of air-therein when the ythrust plate 22 and lrarn 16 are closely adjacent each other. However, as will be seen, the introduction of any appreciable amount of air or other j fluid immediately effects a corresponding movementrof the ram 16.. In this'regard,hydraulic fluid may beV used to expand the bag 24,V but pressurized `air is preferred.

- Asbest illustrated in FIGS. 2 and 3, thebag 24, includes a kcentral opening having tapering marginsnwhich are 33 is connected to a usual and conventional air valve assembly V90 and, as will be `more particularlyL described hereinafter, carries Vhigh pressure air from the assembly Y90 to theinterior of thebag 24 to drive orurge the ram 16 downwardly toward the press bed 12. n l Although various means will immediately suggest themselves to those skilled inthe art for electing upward movelment or return/of the ram 16 after a working stroke, in

the present invention this is preferably yaccomplished by a j plurality of ramjreturn assemblies 91 which, asbest viewed in FIG.V 4, are each constituted ofi an elongated element or rod 92 whose lower extremity -is threadably mounted within a complementally threaded socket 94` provided in the ram 16.` The upper extremity of each rod 92 mounts a stop element or Washer 96, a nut 98,\and;y

a lock nut 100, and a biasing element or compression ably disposed through' suitable openings 104 provided in the thrust plate 22 so that Vthe ram 16 is resiliently supported by the relatively stationary thrust plate 22 but is downwardly movable againstthe bias of the springsf 102 during a working stroke. Upon evacuationfof air from theA interior ofthe bag 24, the `bias of the springs 102 effects a return or upward movement of the ram 16;`

as will be apparent.

' The precise nature of the liuid pressure andcontrol Vapparatus 26 associated with .the thrust plate 22 and the bag 24 will vary somewhat according to the application i for which the press is to be used. In the present embodiment, the apparatus 26 Vis. adapted -to operate the press in such a Vmanner that the ram 16 is driven through a v relatively short'stroke of two to Vthree inches at a rate of approximately 450` strokes per minute,` although this may be adjusted within'certain limits as desired. Ac-

cordingly, the particular apparatus-26 illustrated includes v a usual air supply valve 106 adapted to be connected tor a suitable air pump or the like (not shown), a conventional pressure gauge 108 beingassociated therewith to determine air pressurek in the line. VThe outlet `side of the valve 106 is connected to a usual accumulator tank 110,

andifrom the accumulator 110 the pressurizedair is carried to the valve assembly'90. y

The valve assembly 904 is a conventional quick operatthen through van exhaust muler 114 toatrnosphere. The apparatus for electrically controlling the air valve assembly 9i) includes any one of Y several Vcommercially available solenoid assemblies `116 operative to effect rapid openv ing and closing of the air valve 9d at a rapid rate. The power for energizing the solenoid assembly 116 is controlled by any suitable electrical switch 118 connected by an electrical conduit 2) to a source of power (not shown).

In operation, the actuator 29 comprising the thrust plate 22, the collars 56 and 53, the bag 24, the iluid pressure and control apparatus 26, and the ram return assemblies 91, are associated with the die set assembly 10 by slidably fitting the collars 56 and 58 and the thrust plate 22 over the guide posts 14. 'The lower extremities of the rods 92 of the ram return assemblies 91 are nextV `air is introduced into and exhausted from the bag 24 according to the control of the solenoid assembly 116, as will be apparent to those skilled in the art.

Upon introduction -of pressurized air into the bag 24,V the ram is driven toward the press bed 12. The ram 16 constitutes the principal moving component and undergoes a movement corresponding to each increment of air introduced into the bag Moreover, substantially the same pressure is applied to the ram 16, substantially evenly over the surface thereof, at each position of the ram throughout its working stroke. There is substantially no control lag or backlash and extreme accuracy is afforded. In addition, maintenance of substantially uniform pressure in the bag 24 over a finite period of time results in constant ram pressure over a corresponding period of time, whether this be at the end or at an intermediate point of the working stroke. This is important for certain applications in which metals must be formed according to a precisely correlated relationship of time versus pressure.

The actuator 2t) can be relatively quickly, vertically slidably removed from the die set assembly 10 by demounting the rods 92 from the ram 16 and operating the collars 56 and 58 into their release positions. The actuator can then be associated with other die set assemblies of comparable dimensions whereby a number of such die set assemblies can be stored for use at a moments notice without also having to store the more expensive actuators 20 as well.

Various modifications andchanges may be made with regard to `the foregoing detailed description without departing from the spirit of the invention or the scope of the following claims.

We claim:

V2l. In a press having a stationary bed, a plural-ity of vertical guide posts fixed at their lower extremities to said bed, rand a ram vertically slidably mounted on and directly connected to said posts and defining a die set `area with said bed, an actuator for urging said ram tow-ard said bed, said -actuator comprising:

a thrust plate mountedto said posts above said ram; means operative to maintainsaid thrust plate in xed position upon said posts; i Ia iiexible, unarticulated bag resting upon said ram and connected to said thrust plate, the materialof said bag havingran elasticY characteristic of longitudinal expansion without significant lateral expansion upon introduction of pressurized fluid int-o said bag; land means for introducing ftuidunder pressure into said bag whereby said ram is urged toward said bed. 2. In a press having a stationarybed, a plurality of vertical guide posts fixed at their 'lower extremities to area with said bed, an actuator for urging said cam toward said bed, said actuator comprising:

a thrust plate mounted to said posts adjacent the upper extremities thereof;

split collars including threaded elements operative to -bias said collars and open said splits for vertically slidably mounting said collars upon said posts, and further operative to relax said bias whereby said collars clamp about said posts to maintain said thrust plate in fixed position upon said posts; Y

a flexible, unarticulated bag interposed between said ram and said thrust plate, the material of said bag `having an elastic characteristic of longitudinal expansion without sig-nificant lateral expansion upon introduction :of pressurized duid into said bag;

.and .means for introducing uid unde-r pressure into said bag ,whereby said ram is urged toward said bed.

3. In a press having a die set assembly including a stationary bed, a plurality of vertical guide posts iixed at their lower extremities to said bed, and aram vertically slidably mounted on and directly connected to said posts and defining a die set area withsaid bed, an actuator for urging said ram toward said bed, said actuator comprising:

a thrust plate mounted t-o said posts adjacent the upper extremities thereof and having an opening therethrough; flexible, unarticulated bag interposed between said ram and said thrust plate, the material of said bag 'having an elastic characteristic of longitudinal expansion without significan-t lateral expansion upon introduction Iof pressurized tluid into sai-d bag, said bag including an opening and means securing said bag to said thrust plate with said opening in communication with said opening in said thrust plate;

fluid pressure means including a conduit secured to said thrust plate in communication with said opening thereof for introducing fluid under pressure into said bag whereby said ram is urged toward said bed;

and clamp means operative to maintain said thrust plate in xed position upon said posts, said clamp means being further operative to permit said thrust Vplate'and said bag to be vertically slidably removed lfrom said posts for disassociation of said actuator from said die set assembly whereby said 'actuator may be quickly associated with another, identical die set assembly. Y l

=4. In a press having .a stationary bed, a plurality of vertical guide posts fixed at their lower extremities to said bed, and a ram vertically slidably mounted on and directly connected -to said posts and defining a die set area with said bed, an actuator for urging said ram toward said bed, said actuator comprising:

a thrust plate mounted to said posts above said ram;

means operative to maintain said thrust plate in fixed position upon said posts;

-a flexible, unarticulated bag resting upon said ram 'and connected to said thrust plate, the material of said bag having an Ielastic characteristic of longitudinal expansion for urging said ram Vtoward said bed without significant lateral expansion of said bag upon introduction of pressurized iuid into said bag;

means for introducing fluid under pressure into said A' Ibag wherebyV said ram is urged toward said bed; and ram return means operative upon said ram and tending to urge said ram away from said bed. 5. In a press having a stationary bed, a plurality of vertical guide posts fixed at their lower extremities to said bed, and a ram vertically slidably mounted on and directly connectedto said posts and dening a die set area with said bed, an actuator for urging said ram towar-d said bed, said actuator oomprising Y Y a thrust plate mounted to said posts above said ram;

position upon said posts;

gated elements vertically slidably disposed through said thrust plate, secured at their lower extremities #to said ram, and mounting stop elements at their upper extremities, said ram'return means furtherk including elongated bias means mounted upon saidY elongated elements and engageable at their opposite extremities with said thrust plate and said stop elements for urging said ram'away from said bed. 16. In a pressV having a stationary bed, a plurality Vof vertical guide posts fixed 'at their lower extremities to said bed, and a ram vertically lslidably mounted on and :directly connected to said posts and defining ya, die set area with said bed, Van actu-ator for urging said ram` to-V ward said bed, saidY actuator comprising:

a thrust plate mounted to said posts adjacent the upper extremities thereof;

split collars including threaded elemen-ts operative to bias said collars and open said splits for verticallyy slidably mounting said collars upon said posts, and further operative to relax said bias whereby'said collars clamp about said posts t-o maintain said thrust plate in fixed position upon said posts; Y l

a exible, unarticulated bag interposed between said ra-m and said thrust plate, the material of said bag having an elastic characteristic of longitudinal expansion without significant lateral expansion upon introduction of pressurized iuid into said bag;

' v means for introducing iiuid under `pressure into said bag whereby said ram is urged toward said bed;

-and ram return means operative upon said ram and tending to urge said ram away from said bed.

7. In Va presshaving a die set` assemblyincluding a stationary bed, a lplurality of vertical guide posts fixed at 4their lower extremities to said, bed, and a yram vertically slidably mounted on and directly connected to said posts and defining a die setk area lwith said bed, an actuator forY urging said ramtoward said bed, said actuator comprising:

a thrust plate mounted to said posts adjacent the upper extremities' thereof and having an opening therethrough;

Y a flexible, unarticulated baginterposed between said .ram and said thrust plate, the. material ofV said bag having `an elastic characteristic of longitudinal expansion without significant lateral expansion upon introduction of pressurized uid into said bag, said bag including an opening and means securingrsaid sov bag to said thrust plate with said opening in corn- J munication with said opening in said thrust-plate;

duid pressure mea-ns including a conduit secured to said Vsaid bagto be vertically slidablyremoved from said Y posts for disassociationof said actuator from said die set lassembly whereby said actuator may be Vquickly :associated with another, identical Ydie set assembly; `Y

, a-nd ram return means includingV a 'plurality of elongated elements vertically slidably disposed lthroug'h said thrust,plate secured at their lowerextremities to said ram', and mounting stop elements at their upper i extremities, said ram return means further including elongated bias means mounted upon said elongatedV elements and engageable at their opposite extremities with said thrust plate and said stop elements for urging said ram away from said bed.

8. In a press having a die set assembly Yincluding a stationary bed, ,ai plurality of Avertical guide posts fixed at their lower extremities't-o said bed, and a ram vertically slidablyA mounted `on and directly connected to said posts and defining a die set areaV with said bed, an actuator for urging said ram toward said bed, said actuator comprising:

a thrust plate mounted through; split 4collars including lthreaded elements operative' to 'bias said collars and open said splits for vertically slidably mounting said collars upon said posts, and

further operative toirelax said, bias whereby said collars clamp about said posts to maintain said thrustl plate in fixed position upon said posts; A.

a'ilexible, unarticulatedrbag interposed between A`sa-id` pansion without significant lateral expansion upon introduction of pressurized fluid into said bag, rsaid bag including an opening and jmeans securing said bag to said thrust plate with said opening in communication with said opening in said thrust plate; iiuid pressure means including a conduit secured to said thrust plate in communication with said opening thereof for introducing fluid under pressure into said Y bag whereby said ram is urged toward said bed; and clamp means operative to maintain said thrust Iplate in fixed position upon said posts, said clamp ymeans being, furtheroperative to permit said thrust plate and said bag to be vertically slidably removed from said posts for disassociation of said actuator lfrom said die'set assembly whereby said actuator may be quickly associated with another, identical die` set assembly.l i Y 9. In a press having a die Vset assembly including astationary, substantially rectangular bed, four vertical guide posts fixed at their lower extrem-ities adjacent the four corners of said bed, and :a substantially rectangular ram vertically slidably mounted on and directly connected postsradjacent the' upper extremities thereof and hav. i

ing an opening therethrough;

a flexible, unarticulated bag interposed between said ram and said thrust plate, the material of said bag having an elastic characteristic of longitudinal expansion without Ysignificant Ylateral expansion upon introduction of pressurized fl-uid int-o said bag, said,` Y bag including an opening andY means securing lsaid bag to saidthrust plate with said opening in comi munication with said opening'in said thrust plate; v

Y fluid pressure means including a conduit secured to said l' thrust' plate in Acommunication with said Vopening thereof for introducing ilu-id under pressure into said. 1

bag `wherebyrsaid ram is urged toward said bed;y

and split collars secured to said thrust plate and includl `ing threaded elements operative to bias Vsaid collars Y and open said splits for nvertically slidably mounting ysaid collars upon atr least a pair of saidy posts, :and 'further operative to relax said bias whereby said collars clamp about said posts -to maint-ansaid ,thrustl plate in fixed, position upon said posts.

i Y 10. In a press having a' die ,seti assembly including a stationary bed, a plurality of vertical guide postsV fixed iY at their lower extremities to said bed, and a ram vertil to said'posts adjacent the upper extremities thereof and having an openingy there.

cally slidably mounted on and directly connected to said posts and dening a die set area with said bed, lan actuator for urging said ram'toward said hed, said actuator comprising:

a thrust plate mounted to said posts adjacent the upper extremities thereof and having an opening therethrough;

a exible, unarticulated bag interposed between said ram and said thrust plate, the material of said bag having an elastic characteristic of longitudinal expansion without signicant lateral expansion upon introduction of pressurized iiuid into said bag, said bag including an opening and means securing said 'bag to said thrust plate With said opening in communication with said opening in said thr-ust plate;

uid pressure means including a conduit secured to said fthrust plate in communication with said opening thereof for introducing uid under pressure into said bag whereby said ram is urged toward said bed;

ram return means resiliently suspending said ram from said thrust plate and tending to resist movement of said ram toward said bed and bias said ram away from said bed; i and at least a pair of split collars secured to said thrust plate and including threaded elements operative to ybias said collars and open said splits for vertically slidably mounting said collars upon said posts to References Cited by the Examiner UNITED STATES PATENTS 171,898 `1/76 Wiles 287-133 235,966 12/80 Sammons 1GO-269 X 671,274- 4/01 Fischer 287-133 697,287 4/02 Spaulding 10o-266 X 877,139 1/08 'Datarinof 100-269 1,464,010 8/ 23 Miller 100-257 1,777,310 10/ 30 Hopkinson 144-2811 X 2,363,779 11/44 Duty et al 10U-269 X 2,448,314 8/48 Kavanagh 100-269 X 2,874,392 2/59 Campione 100-269 X 2,958,621 11/ 60 Freeman et al.V 100--269 2,997,083 8/61 Pfefer 144-281l.1 3,127,202 3/64 Koen 287-52 VFOREIGN PATENTS 520,254 3/ 31 Germany.

WALTER A. SCHEEL, Primary Examiner. 

1. IN A PRESS HAVING A STATIONARY BED, A PLURALITY OF VERTICAL GUIDE POSTS FIXED AT THEIR LOWER EXTREMITIES TO SAID BED, AND A RAM VERTICALLY SLIDABLY MOUNTED ON SAID DIRECTLY CONNECTED TO SAID POSTS AND DEFINING A DIE SET AREA WITH SAID BED, AND ACTUATOR FOR URGING SAID RAM TOWARD SAID BED, SAID ACTUATOR COMPRISING: A THRUST PLATE MOUNTED TO SAID POSTS ABOVE SAID RAM; MEANS OPERATIVE TO MAINTAIN SAID THRUST PLATE IN FIXED POSITION UPON SAID POSTS; A FLEXIBLE, UNARTICULATED BAG RESTING UPON SAID RAM AND CONNECTED TO SAID THRUST PLATE, THE MATERIAL OF SAID BAG HAVING AN ELECTRIC CHARACTERISTIC OF LONGITUDINAL EXPANSION WITHOUT SIGNIFICANT LATERAL EXPANSION UPON INTRODUCTION OF PRESSURIZED FLUID INTO SAID BAG; AND MEANS FOR INTRODUCING FLUID UNDER PRESSURE INTO SAID BAG WHEREBY SAID RAM IS URGED TOWARD SAID BED. 